Accounts of 15th century combats single combats and fighting manuals of the period make it clear that the lance was often expected to be thrown early in the fight, and so it should be of a suitable length for throwing. It also needed to be short enough to deal with an opponent that could quickly close range, but not so short that the wielder would seriously disadvantaged fighting against a longer weapon. The illustrated manuals suggest that eight feet might be a reasonable and typical median length for a lance used in single combat, although they could sometimes be as short as 6-6.5’.
George Silver, in his Paradoxes of Defence of 1599, offered this explanation of what he considered the proper length of hafted weapons that included thrusting spears of about this length, the short staff, half pike and partisan:
To know the perfect length of your short staff, or half pike, forest bill, partisan, or glaive, or such like weapons of vantage and perfect lengths, you shall stand upright, holding the staff upright close by your body, with your left hand, reaching with your right hand your staff as high as you can, and then allow to that length a space to set both your hands, when you come to fight, wherein you may conveniently strike, thrust, and ward, & that is the just length to be made according to your stature. And this note, that these lengths will commonly fall out to be eight or nine foot long, and will fit, although not just, the statures of all men without any hindrance at all unto them in their fight, because in any weapon wherein the hands may be removed, and at liberty, to make the weapon longer of shorter in fight at his pleasure, a foot of the staff being behind the backmost hand does no harm. And wherefore these weapons ought to be of the lengths aforesaid, and no shorter, these are the reasons: If they should be shorter, then the long staff, morris pike, and such like weapons over and above the perfect length, should have great advantage over them, because he may come boldly and safe without any guard or ward, to the place where he may thrust home, and at every thrust put him in danger of his life, then can the long staff, the morris pike, or any longer weapon lie nowhere within the compass of the true cross, to cross and uncross, whereby he may safely pass home to the place, where he may strike or thrust him that has the long weapon, in the head, face, or body at his pleasure.
When armies fought the men-at-arms on foot made somewhat different choices, and often used the same lances they would use mounted, without any modifications. In the 14th century a typical length might be 9-9.5’, but this would lengthen to 10-11.5’ in the mid 15th century and later. Contemporary iconography often shows lances of this length used by formations of men-at-arms fighting on foot.
Sometimes, however, the men-at-arms shortened their lances. Froissart reports that the French cut theirs down to five feet in length at Auray and Poitiers, and that the free company composed of mercenaries from many nations under Regnault or Arnaud de Cervoles, called ‘the archpriest’, cut theirs down to “six feet or thereabouts” at Brignais in 1361. Three related accounts of Agincourt, by Monstrelet, Waurin, and Le Fèvre, agree that the French shortened their lances, but do not specify a length.
It is important to understand that lances were not always shortened for massed combat on foot. The fact that the chroniclers saw fit to mention the fact, and only for one side at each battle mentioned, suggests that in those cases it was unusual enough to merit comment.
Silver spoke of the difference between fighting in mass formations and fighting singly or small groups:
Yet understand, that in battles, and where variety of weapons are, among multitudes of men and horses, the sword and target, the two handed sword, battle axe, the black bill, and halberd, are better weapons, and more dangerous in their offense and forces, than is the sword and buckler, short staff, long staff, or forest bill. The sword and target leads upon shot, and in troops defends thrusts and blows given by battle axe, halberds, black bill, or two handed swords, far better than can the sword and buckler.
The morris pike defends the battle from both horse and man, much better than can the short staff, long staff, or forest bill. Again the battle axe, the halberd, the black bill, the two handed sword, and sword & target, among armed men and troops, by reason of their weights, shortness, and great force, do much more offend the enemy, & are then much better weapons, than is the short staff, the long staff, or the forest bill.
Similarly, when large formations were involved, the greater length of unshortened lances could be more effective than shortened ones, particularly against cavalry. And as a practical matter, if a lance for mounted combat was shortened for foot combat, it could not be lengthened again if it was needed later for mounted combat.